In general, a refrigerant compressor is applied to a vapor compression type refrigerating cycle (hereinafter, referred to as ‘refrigerating cycle’), such as a refrigerator or an air conditioner. A constant-speed type compressor driven at constant speed and an inverter type compressor capable of controlling rotation speed have been introduced as the refrigerant compressor.
The refrigerant compressors are categorized as follows. A refrigerant compressor, in which a driving motor (typically, an electric motor) and a compression part operated by the driving motor are all installed in an inner space of a hermetic casing, is referred to as a hermetic type compressor, and a compressor of which the driving motor is separately installed outside the casing is referred to as an open type compressor. Home or commercial cooling apparatuses usually employ the hermetic type compressor. Such hermetic type compressors may be categorized into a reciprocating type, a scroll type, a rotary type and the like according to a refrigerant compression mechanism.
The rotary compressor compresses a refrigerant by use of a rolling piston eccentrically rotating in a compression space of a cylinder and a vane contacted with a rolling piston for partitioning the compression space of the cylinder into a suction chamber and a discharge chamber. In recent time, a variable capacity type rotary compressor capable of varying a cooling capacity of the compressor according to the change in a load has been introduced. Well-known technologies for varying the cooling capacity of the compressor include applying an inverter motor, and varying a volume of a compression chamber by bypassing part of a compressed refrigerant out of a cylinder. However, for employing the inverter motor, a driver for driving the inerter motor is about 10 times as expensive as a driver of a constant-speed motor, thereby rising a fabrication cost of the compressor. On the other hand, for bypassing the refrigerant, a piping system becomes complicated and accordingly a flow resistance of the refrigerant is increased, thereby lowering efficiency of the compressor.
Considering such drawbacks, a so-called independent suction type variable capacity rotary compressor (hereinafter, referred to as ‘independent suction type rotary compressor’), in which a plurality of cylinders are provided and at least one of them is allowed for idling, is introduced. In this case, a suction pipe is independently installed in each of the plurality of cylinders such that both cylinders are operated independent of each other.
However, for the independent suction type rotary compressor, since the suction pipes should independently be connected to both cylinders, the number of assembly processes is drastically increased, thereby rising the fabricating cost of the compressor.
As both of the cylinders are connected by the corresponding suction pipes, a refrigerant of high temperature flows backwardly into an idling cylinder, thereby lowering the function of the compressor.
Further, in case of a plurality of suction pipes being connected, they are positioned near other members, and thereby a welding space therefor is not ensured. Accordingly, an automatic assembly process is not available to be performed, thereby further increasing the fabricating cost.
In addition, a mode switching device for varying the capacity of the compressor is installed outside the casing, accordingly it is vibrated when the compressor is vibrated, thereby aggravating the vibration of the compressor.